Earthquake in Sisak and Banovina

The Experiences of the State Archives in Sisak

Abstract

The series of earthquakes that began in the area of Sisak and Banovina at the end of December 2020 and to some extent still continue caused the loss of seven lives, extensive material damage on out- and residential buildings, including many buildings with the cultural heritage status. The earthquake caused considerable economic and demographical changes, and also endangered movable cultural heritage. As the protector of written cultural heritage in the form of archival records created in this particular area the State Archives in Sisak had also faced this problem and was forced, sadly not for the first time during its 60-year history, to apply rescue measures and records protection in extraordinary conditions.

The buildings in the very centre of Petrinja and Sisak built in the 18th or early 19th century already sustained considerable damage during the first earthquake of magnitude of 5 ML, which occurred on Monday, 28 December at 6:28 am. Among them is the building whose ground floor is used by the State Archives in Sisak for its Petrinja archival centre. It is a single-storey building with adapted loft, on the southern side of Petrinja’s park, built during the mid-18th century and a valuable example of Baroque architecture. The building is owned by the town of Petrinja and the Archives has been the ground floor’s permanent user since 1966.

A much stronger earthquake that occurred the next day, with its magnitude of 6.2 ML, drastically and beyond recognition changed the outlook of Petrinja’s old centre. The majority of buildings around Petrinja’s park, particularly on its east side, were almost completely destroyed. The building where Archival Remote Storage Centre Petrinja operated was not destroyed, but the structural engineer’s examination revealed that damages on the floor, stairs and roof are of such an extent that they impaired its structure and it was therefore marked as unusable. The archives space on the ground floor was thoroughly adapted in 2008 and 2009, the wooden floors with earth base were substituted with reinforced concrete slabs, which was probably one of the reasons this part of the building fared better in the earthquake. However, even though the shelves were loaded with archival records to the maximum extent, the earthquake shattered them like dominos and the records partially fell down, in some cases they fell out from archival boxes.

Under the circumstances the earthquake made the Storage Centre’s further work impossible, while the state of the records meant they were no longer available for users. The notion that Petrinja’s fonds pertaining to administration are the irreplaceable source of information and documents in form of construction documentation (location, construction and occupational permits, together with design documentation) that will be essential for rebuilding the heavily wounded Petrinja dictated swift reaction and particular care during records evacuation to the Archives’ main building in Sisak. Annexed and adapted from 2004 to 2007, apart from minor damage in form of cracks on the cornerstone, outer wall of the old part of the building, the latter fared well during the earthquake. In spite of the major damage of archival shelves and mobile shelving at Sisak’s building, there was enough space for the temporary accommodation of evacuated records from Petrinja.

The evacuation of the mentioned archival and library holdings from the damaged Storage Centre in Petrinja had been successfully undertaken during two workdays, on 8th and 11th January (Friday and Monday) 2021. The total of 218 fonds and 5 collections of archival records had been evacuated, taking up the total of 450 linear meters of shelves, as well as a valuable part of professional archival library in the total quantity of 80.7 linear meters. Since this undertaking required the participants to enter a space within the building that was damaged in the earthquake and hence was marked with a red label, it was carried out by the joint coordination of the Headquarters of Civil Protection, members of the Croatian Mountain Rescue Service, Croatian army which secured some of the transport vehicles for the records, considerable efforts of the State Archives in Sisak’s employees, as well as the enthusiastic assistance of colleagues (4 employees and 2 transport vehicles) from the Croatian State Archives in Zagreb, together with numerous laymen volunteers. Even though particular care was given to the sequence of archival records within individual archival wholes, none the less it took a month following the evacuation to update the status of Petrinja’s fonds and establish order according to existing inventories. Our procedural haste was quickly vindicated by the increased intensity of users’ demands for the very same records that had been evacuated.

Another aggravating factor for the activity of this institution after the earthquake was the damage on mobile shelves and ordinary archival shelves at the State Archives in Sisak’s main building. Unlike the Remote Storage Centre in Petrinja, where the shelves collapsed in domino effect, the shelves in Sisak’s repositories were laterally bent towards the wall, above the passage. The biggest damage befell shelves with the highest amount of records. Even the shelves that were ‘handmade’ in the 1960s from metal profiles 5 mm in width were bent. It was, however, the combination of factors that caused them to become bent: their height (4 meters), being overloaded with archival records, intensity and direction of seismic waves, as well as the fact they were not mutually secured or fixated in the floor or on the celling. Except in several boxes archival records remained on the shelves without sustaining damage. Similar damage was detected on mobile shelving. The existing cross enforcements of individual shelves within the shelving proved insufficient and too weak for the intensity of the earthquake’s seismic waves, particularly with the shelves that were completely filled with archival records.

The determination of damage on records that remained in buildings of individual creators remains slow and difficult due to the fact that entering the majority of buildings where records are kept is not possible or can only be done at one’s own risk because of the damages sustained by buildings. Another aggravating circumstance is the physical absence of employees in charge of individual creators, since they work ‘from home’ due to the pandemic.

It can be concluded that the example of the State Archives in Sisak also confirms in practice that investing in building of new buildings with reinforced concrete construction and high bearing capacity for repositories (up to 10 kN/m²) is a good and justified investment (like it was proposed by the annex and reconstruction project from 2002). While supplying repositories, particularly in potentially seismic active areas like the majority of Republic of Croatia, additional fastening of shelves should be taken into account, both horizontally (diagonally below each shelf), which would prevent the loaded shelf to bend during earthquakes, and mutual fastenings of ordinary shelves in the shape of a cage or fixating them in the celling- or floor panel (assuming they were made from reinforced concrete). Naturally, when it comes to mobile archival shelving it is necessary to perform the mentioned enforcing (in the floor or on the celling) on the fixated units, while the mobile ones should be enforced between the joined units with stronger braces than the ones currently available on the market.